The present invention relates to a plastic film and, especially, to an optical thin film made by insert mold technology and manufacturing processes thereof.
Due to the prevalence of mobile phones and notebooks, users have higher demands for housings of them. Besides requirements of styles and colors, a hardened surface for preventing scratches is also important. The hardening treatment for preventing scratches is applied on electronics such as notebooks, mobile phones, and personal digital assistants (PDA) with a colorful and smooth plastic surface made by injection molding. Besides, it can also be applied to wood panels and wheel rims.
Referring to FIG. 1, a conventional way for surface coating of a film on plastic housings is disclosed. Referring to step S100′, prepare a plastic material made from polycarbonate (PC), polypropylene (PP), polymeric methyl methacrylate (PMMA), methyl methacrylate styrene copolymer (MS), acrylonitrile butadine styrene (ABS), polystyene (PS), polyethylene terephthalate (PET), polyacetal, polyoxy Methylene (POM) or Nylon. Then, take step S110′, forming shape of a housing by injection molding. Run step S120′, painting various figures or colors on surface of the housing by spray coating. During the processes of spray coating, masking paint is used repeatedly to form the figures or words. Referring to step S130′, spray coat transparent curable coating such as extenders or lacquer. Next, take step S140′, spray coat the anti-scratch coating. Finally, run step S150′, use ultraviolet curing treatment to harden the anti-scratch coating.
The method mentioned above paints various figures or colors on surface of housings by spray coating. It takes a long time to use masking paints or to attach adhesive tapes repeatedly. The processes are not only complicated but also generated pollutions and waste of paints caused by a lot of spray. Moreover, most conventional paints contain lead or other heavy metal, so that they violate regulations of Restriction of Hazardous Substance (ROHS). Also, the layer of transparent curable coating causes waste of coating, uneven distribution, and surface roughening. Furthermore, there may be piling due to turnings or curves on surface. Further, this led to a fogging problem, while the optical thin film is treated by heat or ultraviolet light, or the size is not right after being assembled.
Refer Referring to FIG. 2, manufacturing processes of an insert mold decoration technology for printing, forming, and molding of a decorated film are disclosed. Referring to step S200′, provide a transparent optical thin film already being harden treated. Take the step S210′, print preformed figures or colored layer under the optical thin film by direct printing or transfer printing. Refer to step S220′, make the optical thin film form the required shape by hot stamping or thermal vacuum forming. Then, run the step S230′, a plastic material is injected under the figures by injection molding to form a final product.
Referring to FIG. 2A, an optical thin film made by insert mold decoration (IMD) is disclosed. The optical thin film includes a figured layer 2′ under the optical thin film layer 1′ and a plastic material 3′ disposed under the figured layer.
However, the insert mold decoration technology firstly takes the hardening treatment of the optic film and then runs the injection molding procedure. Due to increased hardness, during the following procedures such as heat treatment and injection molding, the optical thin film is easy to have cracks or wrinkles on turnings or corners. Also, it may have fogging.